This invention relates to a golf ball having a soft feel on impact, which offers superior flight performance to even those golf players who swing a driver (W#1) at a low head speed (HS) of 35 m/s or less, and is improved in durability to repeated impact and moldability.
In order for the golf ball to present a soft feel on impact, the core must be made relatively soft. Development works on golf balls have been made not only for high head speeds, but also for low head speeds. For the prior art golf balls intended for low head speeds, a soft feel was obtained at the sacrifice of travel distance. It was difficult to find a good compromise between travel distance and feel.
More specifically, low head speed golf players, who wish to increase the travel distance, tend to use a driver (W#1) having a larger loft angle than high head speed golf players. In this situation, when the ball is hit at a low head speed, the ball launches at a larger angle and receives more spin, which results in a reduction of travel distance. An attempt was thus made to increase the travel distance of the ball by designing a ball structure having a soft core enclosed with a thin cover for thereby minimizing the spin rate of the ball.
For example, JP-A 8-294549 discloses a golf ball comprising a solid core and a cover enclosing the core, characterized in that the core has a hardness corresponding to a deflection amount of at least 3.5 mm under a load of 100 kg and the cover is composed mainly of an ionomer resin and has a Shore D hardness in the range of 50 to 63 and a 300% modulus in the range of 15 to 35 MPa. However, this golf ball does not intend to improve moldability from the standpoint of cover stock flow and fails to provide the satisfactory property of travel distance when hit at low head speeds.
Also, JP-A 2003-175128 discloses a golf ball comprising a cover in which a ternary composite material consisting of rubber, polyolefin and nylon components is admixed with an olefinic resin. In this golf ball, however, the durability to repeated impact of the cover is insufficiently improved.